When we vacationed in Italy, we befriended an engineering student. He later visited us in the United States. While he was here he remarked "your president is better than our prime minister". At the time Silvio Berlusconi was the Italian PM and Bill Clinton was president. I asked, "you mean Clinton is better than Berlusconi?" He said, "No, all your presidents are better!".
Since our founding, we have counted on voter intelligence and their ability to reject obvious scoundrels from obtaining high elective office. We elected presidents with gravitas. Donald Trump changed all that.
In the past, any politician who did any of the following would slink away from politics to "spend more time with his family":
Credibly accused of rape
Consorting with porn actresses
Bragging about grabbing pussies
Making ludicrous (and unfulfilled) promises like Mexico will pay for a border wall.
Sued for or convicted of fraud
Charged with tax evasion
Illegally taking, mishandling and retaining classified documents
Browbeating state and local election officials
Conspiring to interfere with halt the peaceful transfer of power
Losing some 60 court cases and countless recounts in a failed attempt to cling to power
Leaving office in a snit, refusing to appear on his successor's inauguration.
Quoting Hitler, even privately.
Promising to be a dictator (even only on the first day)
Donald Trump, who possesses a remarkable lack of shame, has proved to every future miscreant, felon and reprobate that a tawdry personal life or criminality is no impediment to a successful political career. In fact for those facing criminal charges, simply running for office can be a way to forestall and possibly avoid prosecution.